The present invention relates to linear electric motors.
Such motors conventionally include an inner armature which is adapted to reciprocate and an outer stator which surrounds the armature. Such a stator conventionally includes a plurality of axially extending laminations which respectively have inner edges engaging each other to define a hollow cylindrical bore in which the armature is situated.
Because such laminations are necessarily situated closer to each other at their inner edges than at their outer edges, inasmuch as the inner diameter of the stator is smaller than the outer diameter thereof, a serious problem is encountered in connection with arranging these axially extending stator laminations in such a way that they are properly situated with respect to each other. Thus, the total thickness of all of the laminations will be approximately equal the circumference of the inner cylindrical bore but is much smaller than the outer circumference of the cylindrical stator.
In an attempt to solve this problem, it has been proposed, for example, to situate axially extending spacers between the laminations at their outer edge regions. However, due to small variations in the thickness of the several laminations or the spacers, experience has shown that it is difficult to insure a tightly packed outside circumferential region for the stator as well as a tightly packed bore circumference inasmuch as one of these circumferences can become solidly packed before the other.
Another attempt to solve this problem is shown in U.S. Pat. No. 3,828,211. Thus, according to this patent, the laminations are deformed at the regions of their outer edges so as to occupy at their outer edges a greater space than at their inner edges. The deforming of the laminations according to this patent includes preferably providing each lamination with a channel-shaped portion at its outer edge or forming each lamination inwardly of but adjacent to its outer edge with a hollow rib, so that the engagement between these hollow ribs or the engagement between the above channels will enable the laminations to occupy at the regions of their outer edges more space than at their inner edges. However, none of these expedients are able to compensate properly for variations in the thickness of the laminations because of their inherent stiffness and rigidity with the result that the stator laminations of such a construction become tightly packed at one circumference of the stator before the other circumference thereof. Furthermore, the lamination configuration suggested by the aforesaid patent necessitates the use of complex forming dies and undue working of the electrical grade iron used in the stator laminations.